His brother Earl and his other brother Earl. Sorry, I couldnt resist.
Earlwb, I noticed in your first picture of the three engines, the one in the middle is a beam mount. What brand engine is it and what did it come out of? It looks like my ryobi's except for the crankcase.
Edwin

His brother Earl and his other brother Earl. Sorry, I couldnt resist.
Earlwb, I noticed in your first picture of the three engines, the one in the middle is a beam mount. What brand engine is it and what did it come out of? It looks like my ryobi's except for the crankcase.
Edwin

That was actually made by a small company here in the USA quite a few years ago. I am trying to remember the name of it. But it eludes me at this time. I'll remember eventually. I think the engine was from a large professional size weed trimmer at the time and it was converted for RC use. I keep it because it does have the beam mounting tabs on it. But with the flywheel and magneto it is heavier and it doesn't develop as much power as newer design engines do.

rotation?

Quote:

Originally Posted by earlwb

You only need to rebalance the flywheel if you have machined off some of the excess fins and stuff on it. But even then it may be balanced Ok, so it may be quite minimal if anything. But sometimes there are protrusions or something that when machined off might affect the balance.

Earl, I trimmed some of the flywheel off of my weed eater brand engine it was a pro 150.....but, just looking at the mag, it implies rotation in the Clockwise direction when looking at the engine. I think props are made to run in the other direction? *when I check, the magnet is at the magneto just before TDC running in this direction.

also wondering what the little deal is on the outside of the carb body? Is this simply for the primer? or does it actually pump?

I got 1.7cm for the bore and about 6cm on the stroke... this seems to give me about 50cc... does this seem right to anyone?

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Yeah it does look like you have a engine that runs clockwise. I suppose you could maybe change the timing on it to run counter clockwise if you wanted to.

That looks like an accelerator pump to me. Some of the engines or carbs do have accelerator pumps on them too. It is handy for punching the throttle fast. When you move the throttle the lever should cause the plunger to move too. Of course it could be vacuum controlled also where it only moves if the engine is running.

If you keep the flywheel, you'll need to make the prop adapter to screw onto the crankshaft stub that threading that end of the adapter for the crankshaft. Put on a couple of flats so you can get wrench on it. The other end of the prop adapter can have a short threaded stub shaft and or four bolts for firmly attaching the prop to it.

With that style crankcase you could directly bolt it up to the firewall on a airplane. You can either drill a hole for the crankshaft end or cut it off some too.

earl, how do I change the timing on it?
I mean, if I put the timing before TDC, when turning clockwise, will the engine run?

If I put CDI on it will that do the trick? the selection of pusher props is really limited, and I don't want to run it on the back of the planned ship.
*I just found Master Airscrew makes a 16x10 3 blade pusher.... this might be the ticket..... and zinger has props that run in that direction....

This project is aimed at a 7-8 foot foam winged trainer type plane that flies slow......

The accelerator, or whatever pump is hooked up to the primer pump deal, and the top nipples connect the tank to the carb.

Changing the timing could be pretty tricky. It may not be doable with some engines. Sometimes one can cut a new woodruff key slot on the flywheel of some engines to change the timing. It depends. Sometimes one can shift the coil unit over too. But since they do have pusher props, it likely isn't worth the effort.

For CDI units one can get a RCexl module from many sources, they work quite well.

worth the trouble ?

I 've converted many engines for model use,and some just weren't worth the trouble,but they were fun to experiment with.!

Along with the experience, came some wisdom....it's good to have a running engine to compare things to...A Quadra 35cc is one of my standards,with everything right out front..
You can compare your (50cc?) engine to a Quadra,for ignition timing....Put the Quadra piston at top dead center,and note where the flywheel magnets are,in relation to the coil,exactly.! Then check your unknown engine..That will clarify which way it turns....if they're the same direction,they'll look alike.
Sometimes you can put a prop adapter on the other end,for standard props..

The electronic conversions are usually pretty easy,but you can't normally use the original flywheel because the magnets are too wide,and greatly retard the timing....If an aftermarket flywheel isn't available,it may not be worth the effort.

thanks other brother earl, & earl, I re measured the stroke, I think I was a bit long.

I come up with a nice 30cc, which makes sense to me.

I'm gonna put the zinger pusher prop on it, wondering what would be best for this engine? does an 18x6 or 8 make sense? Or does the 16x10 three blade work out?

I think I'm gonna chuck up some hex steel in the lathe this afternoon, and thread the inside to go on the crank.
Wondering if anyone has used some sort of keeper system to keep the prop shaft from coming unthreaded when idling down?
I was thinking of a hex screw, or possibly drilling through both prop shaft and crankshaft and using a keeper pin?

Since it rotates clockwise, it may have a left hand thread, so that it doesn't come loose when the engine is running, but it would tend to tighten up instead.

Yeah a 18x8 is probably OK as is the 16x10 three blade. Maybe a 20x6 or 20x8 even. Hard to say for sure until you get it running. You might have to try different props on it. The gas two stroke engines tend to act more like four stroke engines in that they like larger props on them.

thanks earl, the thread is normal right hand, I'm worried that when the flywheel(prop) is spinning fast, and I throttle down, the prop will want to turn the same speed and the engine wants to slow down, and it will come off!

I wouldn't worry about the prop coming off....Use some serious locktite on the adapter,and please don't drill any thing for roll pins or bolts.....First that weakens them,and they don't always go back to the same position if you remove and retighten things.

Props don't USUALLY come off,except for a backfire.

Use locking nuts or double ones for insurance....many four strokes have great retaining nuts that tighten securely,and a second one with a taper machined on the end,screws into the first and locks securely.

Got the adapter made, put a pinhole through for a safety wire setup and star washers for the prop. Should work pretty well! Get a prop next week and test the darn thing. * the pinhole is only on the outside, does not go through the shaft!

Wondering what the carb/tank/ pressure line ?setup is for these things?
I'm probably going to make my own muffler, the one that is on it is huge and won't let me easily firewall mount.
Any problem running this thing inverted? I'd like the smoke to go out the bottom

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That looks pretty good. I would make a couple of larger washers for the prop though. You want a wider washer to sandwich the prop in between. Usually the adapter has a wider front to it to also serve as a washer for that side and they sort of knurle the surface or cut grooves to aid in gripping the prop good.